Concrete Calculator
Calculate how much concrete you need in cubic yards, meters, and number of bags.
100% Client-Side
What is Concrete Calculator?
A concrete calculator estimates the volume of concrete needed for a slab, footing, column, or post in cubic yards or bags. Getting the right amount prevents costly waste from over-ordering or project delays from under-ordering.
How to Use
- Select the shape of your project (slab, cylinder, footing, steps)
- Enter the dimensions: length, width, and depth/thickness
- Add a waste percentage (5-10% is typical)
- View the total volume in cubic yards and the number of bags needed
Formula
Volume = Length x Width x Depth. Convert to cubic yards by dividing by 27 (since 27 cubic feet = 1 cubic yard)
Frequently Asked Questions
- How many bags of concrete are in a cubic yard?
- It depends on the bag size. An 80-lb bag yields about 0.6 cubic feet. One cubic yard (27 cubic feet) requires approximately 45 bags of 80-lb concrete.
- How thick should a concrete slab be?
- Standard residential slabs are 4 inches thick. Driveways and garage floors should be 5-6 inches. Heavy-load areas may require 8+ inches with reinforcement.
- How much extra concrete should I order?
- Order 5-10% more than calculated to account for uneven ground, form deflection, and spillage. Running short mid-pour creates weak joints in the finished concrete.